In vivo sensing devices, such as thermometers, pH meters, optical scanners, image sensors and so on, may be used for example to unobtrusively monitor bodily systems and in vivo sites. Some in vivo sensors move through body lumens and may be remotely controlled. However, it may sometimes be desirable to immobilize a sensing device in vivo for continuous sensing of an in vivo site, for example, for post surgery monitoring. Other in vivo sensors may perform treatment functions and may be immobilized to perform such treatment. Still other in vivo sensors may be immobilized to monitor an area for a period of time in order to make a diagnosis, such as an in vivo pH sensor which may be immobilized to detect, record and analyze gastroesophageal pH. Immobilization of a device may also provide an opportunity for the device to release a compound such as a drug at a specific location or for taking a biopsy at such location.